// Copyright (C) 2015 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gerrit.server.change;

import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.entities.Project;
import com.google.gerrit.exceptions.StorageException;
import com.google.gerrit.index.query.QueryParseException;
import com.google.gerrit.server.InternalUser;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.query.change.ChangeQueryBuilder;
import com.google.gerrit.server.query.change.ChangeQueryProcessor;
import com.google.gerrit.server.update.BatchUpdate;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.TimeUnit;

@Singleton
public class AbandonUtil {
  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final Provider<ChangeQueryProcessor> queryProvider;
  private final Supplier<ChangeQueryBuilder> queryBuilderSupplier;
  private final BatchAbandon batchAbandon;
  private final InternalUser internalUser;

  @Inject
  AbandonUtil(
      InternalUser.Factory internalUserFactory,
      Provider<ChangeQueryProcessor> queryProvider,
      Provider<ChangeQueryBuilder> queryBuilderProvider,
      BatchAbandon batchAbandon) {
    this.queryProvider = queryProvider;
    this.queryBuilderSupplier = Suppliers.memoize(queryBuilderProvider::get);
    this.batchAbandon = batchAbandon;
    internalUser = internalUserFactory.create();
  }

  public void abandonInactiveOpenChanges(
      BatchUpdate.Factory updateFactory,
      long abandonAfterMillis,
      boolean abandonIfMergeable,
      String message) {
    if (abandonAfterMillis <= 0) {
      return;
    }
    try {
      String query = "status:new age:" + TimeUnit.MILLISECONDS.toMinutes(abandonAfterMillis) + "m";
      if (!abandonIfMergeable) {
        query += " -is:mergeable";
      }

      ImmutableList<ChangeData> changesToAbandon =
          queryProvider
              .get()
              .enforceVisibility(false)
              .query(queryBuilderSupplier.get().parse(query))
              .entities();
      ImmutableListMultimap.Builder<Project.NameKey, ChangeData> builder =
          ImmutableListMultimap.builder();
      for (ChangeData cd : changesToAbandon) {
        builder.put(cd.project(), cd);
      }

      int count = 0;
      ImmutableListMultimap<Project.NameKey, ChangeData> abandons = builder.build();
      for (Project.NameKey project : abandons.keySet()) {
        List<ChangeData> changes = getValidChanges(abandons.get(project), query);
        try {
          batchAbandon.batchAbandon(updateFactory, project, internalUser, changes, message);
          count += changes.size();
        } catch (Exception e) {
          StringBuilder msg = new StringBuilder("Failed to auto-abandon inactive change(s):");
          for (ChangeData change : changes) {
            msg.append(" ").append(change.getId().get());
          }
          msg.append(".");
          logger.atSevere().withCause(e).log("%s", msg);
        }
      }
      logger.atInfo().log("Auto-Abandoned %d of %d changes.", count, changesToAbandon.size());
    } catch (QueryParseException | StorageException e) {
      logger.atSevere().withCause(e).log(
          "Failed to query inactive open changes for auto-abandoning.");
    }
  }

  private List<ChangeData> getValidChanges(Collection<ChangeData> changes, String query)
      throws QueryParseException {
    List<ChangeData> validChanges = new ArrayList<>();
    for (ChangeData cd : changes) {
      String newQuery = query + " change:" + cd.getId();
      ImmutableList<ChangeData> changesToAbandon =
          queryProvider
              .get()
              .enforceVisibility(false)
              .query(queryBuilderSupplier.get().parse(newQuery))
              .entities();
      if (!changesToAbandon.isEmpty()) {
        validChanges.add(cd);
      } else {
        logger.atFine().log(
            "Change data with id \"%s\" does not satisfy the query \"%s\""
                + " any more, hence skipping it in clean up",
            cd.getId(), query);
      }
    }
    return validChanges;
  }
}